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[ AWS Monitoring : CloudWatch ]

[ CloudWatch Metrics ]

- CloudWatch provides metrics for every services in AWS

- Metric is a variable to monitor (CPUUtilization, NetworkIn..)

- Metrics belong to namespaces

- Demension is an attribute of a metric (instance id, environment, etc...)

- Up to 10 dimensions per metric

- Metrics have timestamps

- Can create CloudWatch dashboards of metrics

[ EC2 Detailed monitoring ] 

- EC2 instance metrics have metrics "every 5 minutes"

- With detailed monitoring (for a cost), you get data "every 1 minute"

- Use detailed monitoring if you want to scale faster for your ASG

- The AWS Free Tier allows us to have 10 detailed monitoring metrics

※ Note : EC2 Memory usage is by default no pushed (must be pushed from inside the instance as a custom metric)

[ CloudWatch Custom Metrics ]

2주 과거, 2시간 미래의 매츠릭 데이터 포인트 사용 가능 (EC2 instance 시간이 정확하게 맞춰져있어야 함)

PutMetricData API 호출을 통해 커스텀 매트릭을 CloudWatch에  보낼 수 있음

- Possibility to define and send your own custom metrics to CloudWatch

- Example : memory(RAM) usage, disk space, number of logged in users

- Use API call PutMetricData

- Ability to use dimensions (attributes) to segment metrics

  -- Instance.id

  -- Environment.name

- Metric resolution (StorageResolution API parameter - two possible value) :

  -- Standard : 1 minute (60 seconds)

  -- High Resolution : 1/5/10/30 second(s) - Higher cost

※ Important : Accepts metric data points two weeks in the past and two hours in the future (make usre to configure your EC2 instance time correctly)

[ CloudWatch Dashboards ]

여러개의 AWS Account 및 regions 의 그래프를 대시보드에 사용 가능

- Great way to setup custom dashboards for quick access to key metrics and alarms

- Dashboards are global

- Dashboards can include graphs from different AWS accounts and regions ***

- You can change the time zone & time range of the dashboards

- You can setup automatic refresh (10s, 1m, 2m, 5m, 15m)

- Dashboards can be shared with people who don't have an AWS account (public, email address, 3rd party SSO provider through Amazon Cognito)

- Pricing :

  --  3 dashboards (up to 50 metrics) for free

  -- $3 per dashboard per month afterwards